[Efficacy and safety of pylorus-preserving gastrectomy for early gastric cancer located in the middle third of the stomach: a meta-analysis].

Objective: It is yet to be clarified whether pylorus-preserving gastrectomy (PPG) for early gastric cancer will bring the risk of radical tumor resection, whether it will increase the incidence of postoperative complications, and how much is the benefit of the quality of life for patients after surgery, these issues are not clear. This meta-analysis aims to evaluate the efficacy and safety of pylorus-preserving gastrectomy (PPG) for early middle gastric cancer. Methods: The Chinese and English literatures about PPG and distal gastrectomy (DG) for early gastric cancer were searched from PubMed, Embase, The Cochrane Library, Web of Science, CNKI net and Wanfang database. Literature inclusion criteria: (1) Prospective or retrospective cohort study of PPG and DG for early middle-third gastric cancer published publicly; (2) Patients with early middle-third gastric cancer; (3) The enrolled literatures include at least one of the following outcome indicators: the efficacy indicators include gallstone, residual gastritis, bile reflux, delayed gastric emptying, dumping syndrome, reflux esophagitis and overall complication; the long-term prognostic indicators include 5-year survival rate and 5-year tumor recurrence. Literature exclusion criteria: (1) Reviews, case reports, conference summaries and other non-control studies; (2) Repeated published studies, incomplete studies and unextractable studies; (3) The depth of tumor invasion exceeding submucosa. The search time ended in July 2020. The basic information and evaluation indicators included in the article were extracted. The retrospective study was evaluated using Newcastle-Ottawa literature quality evaluation scale. The prospective randomized controlled study was evaluated using Jadad modified scale. Meta-analysis was performed using Review Manager 5.3. Publication bias was assessed using funnel map. Publication bias was tested using Egger tools. Results: A total of 717 literatures were retrieved, and 17 literatures were enrolled finally, including 2 randomized controlled trials and 15 retrospective studies. A total of 2427 patients were enrolled, including 948 in PPG group and 1479 in DG group. The meta-analysis of the efficacy indicators showed that there were significant differences in gallstones incidence (OR=0.42, 95% CI: 0.28-0.65, P<0.001), residual gastritis incidence (OR=0.50, 95% CI: 0.32-0.77,P=0.002), bile reflux incidence (OR=0.30, 95% CI: 0.20-0.45, P<0.001), delayed gastric emptying incidence (OR=2.40, 95% CI:1.67-3.45, P<0.001), and postoperative dumping syndrome incidence (OR=0.28, 95% CI: 0.15-0.51, P<0.001), while there were no significant differences in postoperative overall complications (OR=0.97, 95% CI: 0.69-1.35, P=0.840), reflux esophagitis incidence (OR=0.79, 95% CI: 0.39-1.61, P=0.520) between the two groups. The meta-analysis of the long-term prognostic indicators showed that no significant differences of 5-year survival (OR=1.02, 95% CI: 0.61-1.71, P=0.940) or 5-year tumor recurrence (OR=0.77, 95% CI: 0.36-1.68, P=0.520) were observed between the two groups. Conclusion: The incidences of gallstone, residual gastritis, dumping syndrome, bile reflux are lower after PPG in early gastric cancer, while the postoperative overall complications and long-term survival are comparable between PPG and DG, indicating that PPG is quite safe and feasible.